A control device includes a force detector configured to detect a force in a normal direction and a force in a shearing direction of fingertips of a robot hand device respectively as a normal force and a shearing force, and an object detector configured to calculate a friction coefficient using the normal force and the shearing force detected by the force detector and to detect whether or not a thin-film object having a maximum friction coefficient different from a maximum stationary friction coefficient between the fingertips is grasped between the fingertips on the basis of the calculation result.
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1. A control device comprising: a force detector configured to detect a force in a normal direction and a force in a shearing direction of fingertips of a robot hand device respectively as a normal force and a shearing force; and an object detector configured to calculate a friction coefficient using the normal force and the shearing force detected by the force detector and for detecting whether or not a thin-film object having a maximum friction coefficient different from a maximum stationary friction coefficient between the fingertips is grasped between the fingertips on the basis of the calculation result.
A robot control system uses force sensors on the robot's fingertips to measure normal force (perpendicular to the finger) and shearing force (parallel to the finger). An object detector then calculates a friction coefficient from these force measurements. The system determines if the robot is grasping a thin, flexible object (like a film) by comparing the calculated friction coefficient to a pre-determined threshold. This threshold is based on the maximum friction expected between the robot's fingertips and assumes the thin-film object has a different maximum friction coefficient.
2. The control device according to claim 1 , further comprising a position detector configured to detect a position of the fingertips, wherein the object detector further detects whether or not a non-thin-film object thicker than the thin-film object is grasped between the fingertips on the basis of the detection result of the position detecting means, wherein if the detection result indicates that the non-thin-film object is grasped between the fingertips, the object detector prohibits the detection of whether or not the thin-film object is grasped between the fingertips, and wherein if the detection result indicates that the non-thin-film object is not grasped between the fingertips, the object detector commences the detection of whether or not the thin-film object is grasped between the fingertips.
The robot control system from the previous description also includes position sensors on the fingertips. If the position sensors indicate that a thick (non-thin-film) object is being grasped, the system disables the thin-film object detection. If the position sensors indicate a thick object is NOT being grasped, then the system enables the thin-film object detection, calculating friction coefficient from normal and shearing forces to determine if a thin-film object is present. This prevents the system from falsely identifying thick objects as thin films based on friction alone.
3. The control device according to claim 1 , wherein the object detector compares a threshold value preliminarily determined from the maximum stationary friction coefficient between the fingertips with the friction coefficient and detects whether or not the thin-film object is grasped between the fingertips on the basis of the comparison result.
The robot control system determines whether a thin, flexible object (like a film) is grasped by comparing a calculated friction coefficient against a threshold. This friction coefficient is derived from normal and shearing forces detected by sensors on the robot's fingertips. The threshold value represents the maximum stationary friction coefficient between the fingertips when no object, or a non-thin-film object, is present. If the calculated friction coefficient exceeds this pre-determined threshold, the system concludes that the robot is grasping a thin-film object.
4. A control method comprising the steps of: detecting, using a force detector, a force in a normal direction and a force in a shearing direction of fingertips of a robot hand device respectively as a normal force and a shearing force; and calculating, using an object detector, a friction coefficient using the detected normal force and the detected shearing force and to detect whether or not a thin-film object having a maximum friction coefficient different from a maximum stationary friction coefficient between the fingertips is grasped between the fingertips on the basis of the calculation result.
A robot control method involves measuring the normal and shearing forces on a robot hand's fingertips using force sensors. Based on these force measurements, a friction coefficient is calculated. This friction coefficient is then used to determine if the robot hand is grasping a thin, flexible object that has a maximum friction coefficient different from the maximum stationary friction coefficient between the fingertips themselves. This determination is based entirely on the calculated friction.
5. A non-transitory, computer-readable medium comprising instructions for executing a control process that includes the steps of: causing a computer to detect a force in a normal direction and a force in a shearing direction of fingertips of a robot hand device respectively as a normal force and a shearing force; and causing the computer to calculate a friction coefficient using the detected normal force and the detected shearing force and to detect whether or not a thin-film object having a maximum friction coefficient different from a maximum stationary friction coefficient between the fingertips is grasped between the fingertips on the basis of the calculation result.
A computer program, stored on a non-transitory medium, controls a robot hand by performing the following steps. First, it reads normal and shearing forces from force sensors located on the robot's fingertips. Then, it calculates a friction coefficient based on these force readings. Finally, it determines whether the robot hand is grasping a thin, flexible object. This is done by comparing the calculated friction coefficient to a pre-determined threshold, where a thin-film object is expected to exhibit a different maximum friction coefficient than the fingertips themselves.
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November 18, 2009
August 13, 2013
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